Before the Dodgers' 7-2 victory over the New York Mets on Tuesday at Citi Field, the 28-year-old right-hander was examined by team physician Neal ElAttrache in Los Angeles. ElAttrache will perform the operation, commonly known as Tommy John surgery.

Billingsley, who was 1-0 with a 3.00 earned-run average in two starts this season, figures to be back around May 2014. When Billingsley returns, he will be in the final guaranteed year of his three-year, $35-million contract. His deal also includes a $14-million club option for 2015, which the Dodgers can buy out for $3 million.

Billingsley first injured his elbow Aug. 24 in a start against the Miami Marlins and could have elected for surgery shortly after. But doing so would have sidelined him for the season, so he opted for injections of platelet-rich plasma and rehabilitation. The Dodgers backed, if not encouraged, the decision, pointing out that 10% to 20% of pitchers who undergo Tommy John surgery fail to regain their form.

Knowing what he knows now, General Manager Ned Colletti said that he was still comfortable with the decision-making process.

"Everybody did everything they could," Colletti said.

The Dodgers were cautious when rehabilitating Billingsley, who tested his elbow in gradual steps over several weeks. He played catch. He long tossed. He long tossed at a longer distance. He threw off a mound. He threw off a mound at 90 mph.

If Billingsley had felt significant pain at any point, the Dodgers would have pushed him to have surgery.

"Each time, I passed with flying colors," Billingsley said during spring training when recalling the rehabilitation process.

The final exam consisted of two simulated games in late October at the team's spring-training complex in Arizona. With his fastball touching 94 mph in the second game, Billingsley was told to spend the off-season like any other.

Billingsley didn't experience any elbow problems in spring training. He stared the season on the disabled list, but that was because of a bruised finger.

"As the spring went on, we got more confident," Mattingly said. "He wasn't having any problems. He was able to make all of his pens. He wasn't having any problems between starts."

Until Friday.

Throwing a light bullpen session in Baltimore, Billingsley said something didn't feel right. A day later, he became the third Dodgers starting pitcher to land on the 15-day disabled list in nine days. The others were Greinke, who fractured his collarbone in a brawl against the San Diego Padres, and Capuano, who strained a calf muscle running in from the bullpen to defend Greinke.

"Most years, you're probably going to need eight to 10 [starters], right?" Mattingly said. "Somebody usually goes down here or down there. You probably wouldn't think you'd need them in the first 20 days."

Of the eight starting pitchers the Dodgers had at the start of the season, only Harang was traded, in part because their excess starters weren't in demand and in part because some club officials were still uncertain whether Billingsley's elbow would hold up.

The Dodgers rotation now consists of Clayton Kershaw, Lilly, Ryu, Josh Beckett and recent triple-A call-up Stephen Fife. Lilly, who underwent shoulder surgery last year, will make his season debut Wednesday. The game will be his first since May.

Mattingly downplayed concerns about the rotation, saying the timing of the injuries is making the situation look worse than it is.

"We're getting Teddy back tomorrow," he said. "We think Cap's going to be back quickly. And we're going to get Zack back. It's not like we lost everybody. We just got a flood of it pretty quick."

Zach Lee, the Dodgers' first-round pick in 2010, could soon offer another option. Lee, 21, is 2-0 with a 1.17 ERA in four starts with double-A Chattanooga.